<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html><head><title>R: Visual Acuity in Left and Right Eyes</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<link rel="stylesheet" type="text/css" href="R.css">
</head><body>

<table width="100%" summary="page for VisualAcuity"><tr><td>VisualAcuity</td><td align="right">R Documentation</td></tr></table>

<h2>Visual Acuity in Left and Right Eyes</h2>

<h3>Description</h3>


<p>Data from Kendall &amp; Stuart (1961) on unaided vision among 3,242 men
and 7,477 women, all aged 30-39 and employed in the U.K. Royal
Ordnance factories 1943-1946.
</p>


<h3>Usage</h3>

<pre>
data("VisualAcuity")
</pre>


<h3>Format</h3>


<p>A data frame with 32 observations and 4 variables.
</p>

<dl>
<dt>Freq</dt><dd><p>frequency of visual acuity measurements.</p>
</dd>
<dt>right</dt><dd><p>visual acuity on right eye.</p>
</dd>
<dt>left</dt><dd><p>visual acuity on left eye.</p>
</dd>
<dt>gender</dt><dd><p>factor indicating gender of patient.</p>
</dd>
</dl>



<h3>Source</h3>


<p>M. Friendly (2000),
Visualizing Categorical Data:
<a href="http://euclid.psych.yorku.ca/ftp/sas/vcd/catdata/vision.sas">http://euclid.psych.yorku.ca/ftp/sas/vcd/catdata/vision.sas</a>
</p>


<h3>References</h3>


<p>M. G. Kendall &amp; A. Stuart (1961),
<EM>The Advanced Theory of Statistics</EM>, Vol. 2.
Griffin, London.
</p>
<p>M. Friendly (2000),
<EM>Visualizing Categorical Data</EM>.
SAS Institute, Cary, NC.
</p>


<h3>Examples</h3>

<pre>
data("VisualAcuity")
structable(~ gender + left + right, data = VisualAcuity)
</pre>


</body></html>
